Dual aperture dual modem satcom terminal

ABSTRACT

An aircraft based satellite communication (SATCOM) terminal includes a broadband aperture configured to communicate through non-geostationary orbit (NGSO) satellites for broadband communications, a management aperture configured to receive NGSO satellite management information from a geostationary orbit (GSO) satellite, and at least one processor that performs operations. The operations receive the NGSO satellite management information from the GSO satellite, where the NGSO satellite management information indicates positions and associated time of a set of the NGSO satellites. The operations acquire a second communication link with a second NGSO satellite among the set using the NGSO satellite management information during handoff switching from using a first communication link that was previously acquired with a first NGSO satellite to using the second communication link being acquired with the second NGSO satellite. The operations then perform broadband communications through the broadband aperture and the second communication link with the second NGSO satellite. Related ground-based control centers are disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.17/406,327, filed on Aug. 19, 2021, which claims the benefit of U.S.Provisional Patent Application Ser. No. 63/188,001, filed on May 13,2021, the disclosure and content of which are incorporated by referenceherein in their entireties.

FIELD

The present disclosure relates to aeronautical broadband communicationsystems including satellite communication systems for aircraft.

BACKGROUND

Commercial aircraft provide broadband data traffic communications, e.g.,Internet, for passengers through satellite communication systems. Thesesystems are being designed for use of mixed orbit inflight connectivityservice where service will be delivered from satellites that are a mixof Non Geostationary Orbit (NGSO) Satellite and Geostationary Orbit(GSO) Satellite. NGSO includes Medium Earth Orbit (MEO), Low Earth Orbit(LEO), and Highly Elliptical Orbit (HEO) satellites. GSO includesGeosynchronous Equatorial Orbit (GEO) satellites. FIG. 1 illustratesaeronautical communications services provided through NGSO satellitesoverlaid by a GSO satellite.

A commercial broadband system using NGSO satellites for aircraftcommunications has not yet been demonstrated. SpaceX recently shared itsintention of extending the Starlink (LEO Broadband System) service toaircraft in its blanket license application to FCC. Over decades,aeronautical broadband service has been primarily delivered using GSOsatellites. With the introduction of the next-generation LEO satelliteconstellations, airline operators are eager to offer passengerlow-latency high-speed inflight connectivity. However, the aeronauticalantenna and modem technology will have substantial challenges. Somechallenges that arise when attempting to deliver inflight connectivityto commercial aviation using next-generation NGSO satellites, primarilyLEO satellites, include the following:

-   -   1) Approximate broadband communication service disruption of        about 7 seconds occurring every 5 to 6 minutes;    -   2) Higher probability of acquisition failure when attempting to        join the moving NGSO satellite;    -   3) Frequent occurrences of aircraft satellite communication        systems needing to operate without access to accurate        information needed to assist with tracking the ever moving fleet        of NGSO satellites; and    -   4) Waste of large bandwidth due to replication of multicast        terrestrially and over the NGSO satellites.

SUMMARY

Some embodiments of the present disclosure are directed to an aircraftbased satellite communication (SATCOM) terminal that includes abroadband aperture, a management aperture, at least one processor, andat least one memory storing instructions executable by the at least oneprocessor to perform operations. The broadband aperture is configured tocommunicate through non-geostationary orbit (NGSO) satellites forbroadband communications. The management and broadcast-multicastaperture is configured to receive, from a geostationary orbit (GSO)satellite, NGSO satellite management information. The operations receivethe NGSO satellite management information from the GSO satellite, wherethe NGSO satellite management information indicates positions andassociated time of a set of the NGSO satellites. The operations acquirea second communication link with a second NGSO satellite among the setusing the NGSO satellite management information during handoff switchingfrom using a first communication link that was previously acquired witha first NGSO satellite to using the second communication link beingacquired with the second NGSO satellite. The operations performbroadband communications through the broadband aperture and the secondcommunication link with the second NGSO satellite.

Accordingly, the aircraft based SATCOM terminal can more quickly andreliably acquire the second communication link with the second NGSOsatellite by its use of the NGSO satellite management information whichindicates positions and associated time of a set of the NGSO satellites,including the second NGSO satellite.

In some further embodiments disclosed herein, the operations may controldirectional pointing of the broadband aperture based on a position ofone of the NGSO satellites determined from the NGSO satellite managementinformation to acquire the second communication link with the NGSOsatellite. The operations may control transmitter and/or receiversignaling timing for acquiring the second communication link with thesecond NGSO satellite, based on location of the second NGSO satelliteindicated by the NGSO satellite management information and based onlocation of an aircraft transporting the SATCOM terminal as obtainedfrom a communication bus of the aircraft. The operations may controltransmission power level through the management and broadcast-multicastaperture toward the second NGSO satellite based on the position of thesecond NGSO satellite indicated by the NGSO satellite managementinformation and based on position of an NGSO satellite gateway Earthstation which is indicated by the NGSO satellite management informationand which is serving the second NGSO satellite, to acquire thecommunication link with the second NGSO satellite.

In some further embodiments disclosed herein, the operations mayestimate frequency to be used for receiving signaling from the secondNGSO satellite during acquisition and/or to be used for transmittingsignaling to the second NGSO satellite during acquisition, based onfrequency drift indicated by the NGSO satellite management informationfor the second NGSO satellite and for an NGSO satellite gateway Earthstation serving the second NGSO satellite. The operations may estimatefrequency to be used for receiving signaling from the second NGSOsatellite during acquisition and/or to be used for transmittingsignaling to the second NGSO satellite during acquisition, based on thespeed and direction of the second NGSO satellite indicated by the NGSOsatellite management information and based on speed and direction of anaircraft transporting the SATCOM terminal as obtained from a bus of theaircraft.

In some further embodiments disclosed herein, the SATCOM terminalincludes a broadband modem coupled to the broadband aperture and whichis configured by the operations to establish the second communicationlink for bidirectional communications through the second NGSO satelliteusing the NGSO satellite management information, and includes amanagement and broadcast-multicast modem coupled to the management andbroadcast-multicast aperture and which is configured by the operationsto receive the NGSO satellite management information from the GSOsatellite.

Some other embodiments are directed to a related ground-based controlcenter that includes at least one network interface configured tocommunicate through at least one GSO satellite gateway Earth stationwith a GSO satellite, a processor, and at least one memory storinginstructions executable by the at least one processor to performoperations. The operations generate NGSO satellite managementinformation indicating positions and associated time of a set of NGSOsatellites, and communicate the NGSO satellite management informationthrough the at least one GSO satellite gateway Earth station and the GSOsatellite to aircraft based SATCOM terminals configured to use the NGSOsatellite management information to acquire the NGSO satellites in theset during handoff switching between the NGSO satellites in the set forbroadband communications.

Other aircraft based SATCOM terminals and ground-based control centers,and related methods, and computer program products according toembodiments of the inventive subject matter will be or become apparentto one with skill in the art upon review of the following drawings anddetailed description. It is intended that all such additional aircraftbased SATCOM terminals and ground-based control centers, and relatedmethods, and computer program products be included within thisdescription, be within the scope of the present inventive subjectmatter, and be protected by the accompanying claims. Moreover, it isintended that all embodiments disclosed herein can be implementedseparately or combined in any way and/or combination.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and are incorporated in a constitute apart of this application, illustrate certain non-limiting embodiments ofinventive concepts. In the drawings:

FIG. 1 illustrates aeronautical communications services provided throughNGSO satellites overlaid by a GSO satellite;

FIG. 2 illustrates a block diagram of a dual aperture dual modem for anaircraft based SATCOM terminal which is configured according to someembodiments of the present disclosure;

FIG. 3 illustrates a block diagram with indicated communications for theground based and combined GSO and NGSO satellite system according tosome embodiments of the present disclosure;

FIG. 4 illustrates example velocity vectors of a pair of LEO satellitesrelative to an aircraft velocity vector;

FIG. 5 illustrates a block diagram of an aircraft based SATCOM terminalaccording to some embodiments of the present disclosure;

FIG. 6 illustrates system components that are used for multicastingcontent through a GEO satellite and for multicasting the same contentthrough LEO satellites according to some embodiments of the presentdisclosure;

FIGS. 7-10 illustrates block diagrams of various aircraft based SATCOMterminals which are configured according to some embodiments of thepresent disclosure; and

FIG. 11 illustrates a block diagram of a dual aperture dual modem SATCOMterminal which is configured according to some embodiments of thepresent disclosure.

DETAILED DESCRIPTION

Inventive concepts will now be described more fully hereinafter withreference to the accompanying drawings, in which examples of embodimentsof inventive concepts are shown. Inventive concepts may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein. Rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of various present inventive concepts to thoseskilled in the art. It should also be noted that these embodiments arenot mutually exclusive. Components from one embodiment may be tacitlyassumed to be present or used in another embodiment.

Inflight broadband connectivity hasn't been delivered over LEOsatellites because of the challenges that have been described above andherein. Broadband connectivity has been demonstrated through MEO (O3B)satellites as a proof of concept through a test flight using a singleaperture-single beam antenna. Because of the relatively lower recurrenceof the satellite switch, the velocity of the satellites, and thepredictability of the orbit, the challenges for providing broadbandconnectivity through MEO satellites were not as extensive as forproviding broadband connectivity through LEO satellites.

However, current antenna and modem technology are not adequate toprovide inflight broadband connectivity through LEO satellites.Implementing inflight broadband connectivity with current antenna andmodem technology faces new challenges, which include:

-   -   1) Higher recurrence of satellite switching, e.g., nominally        every 5-6 minutes;    -   2) Disruption of service for approximately 7 seconds every 5-6        minutes;    -   3) Higher probability packet drop due to large variation in        propagation delay;    -   4) Lag and lapse in tracking information of several satellites        in mixed orbits of different inclination;    -   5) No or inaccurate satellite position and time information when        an aircraft is returned to service after being grounded, e.g.,        for maintenance; and    -   6) Large consumption of bandwidth for multicast television        delivery.

Various embodiments of the present disclosure are directed to addressingone or more of the above challenges. Some embodiments are directed to aground based control center (300 FIG. 3 ) that broadcasts NGSOmanagement information through a GSO gateway Earth station and GSOsatellite to aircraft within the GSO satellite footprint. The aircraftbased SATCOM terminals are configured to use the received NGSOmanagement information to assist with acquiring NGSO satellites andperforming handoff switching between NGSO satellites for broadbandcommunications. The NGSO satellites can include, without limitation,Medium Earth Orbit (MEO), Low Earth Orbit (LEO), and/or HighlyElliptical Orbit (HEO) satellites. The NGSO management informationbroadcasted through the GSO satellite informs the aircraft based SATCOMterminals in real-time using GSO satellite pathway providing out of bandaccess to the NGSO satellite position and associated time, satellitevelocity, and/or other information. Some of these embodiments are alsodirected to providing spectral resource efficient delivery of televisionusing multicast through GSO satellites, which can be provided inconjunction with the NGSO management information. The term “NGSOmanagement information” is also referred to herein as “managementinformation” and “management and control information.”

Aircraft Based SATCOM Terminal

An aircraft based SATCOM terminal can be configured with a dual aperturedual modem in accordance with some embodiments. FIG. 2 illustrates ablock diagram of a dual aperture dual modem for an aircraft based SATCOMterminal which is configured in accordance with some embodiments.

Referring to FIG. 2 , the modem is configured to receive managementinformation via a management path (also referred to as “managementplane”) through a GSO satellite. The management information is used toconfigure broadband data communications via a broadband path (alsoreferred to as “traffic plane”) through NGSO satellites. The antennasystem includes a dual aperture: 1) a broadband aperture 230 configuredand operated for communicating through NGSO satellites; and 2) amanagement aperture 200 configured and operated for receiving managementinformation through GSO satellites.

The dual aperture antenna may be a horn array or an electrically scannedphased array. Electronically scanned phased array antenna generallyrequire two apertures—each for transmit and receive. The receiveaperture can create two independent and electronically steerable receivebeams. One beam may provide a function as receive path of the broadbandaperture steered towards NGSO satellites (e.g., LEO satellites). Thesecond beam is operated as the receive path of management aperturesteered towards the GEO satellite. The second physical aperture of anelectronically scanned phased array can function as transmit path of thebroadband aperture steered towards the NGSO satellites (e.g., LEOsatellites).

The broadband aperture 230 functions as a primary broadbandcommunication antenna terminal with a bidirectional (transmit andreceive) aperture configured to provide a high slew rate with an abilityto track NGSO satellites, such as LEO satellites, while operating atcruising speed of commercial aircraft. The broadband communications caninclude passenger inflight entertainment traffic, such as streamingmovies, streaming music, streaming games, file transfers, Internetbrowser data, etc., from network content servers via the Internet,cellular data (e.g., phone calls) from a cellular network, crewcommunications, aircraft operations and maintenance data, etc.Performance characteristics of the terminal can be configured to meet orexceed the operating threshold of LEO broadband services.

The management aperture 200 functions as a unidirectional (receive only)antenna with an ability to track a minimum of GEO satellites whileoperating at the cruising speed of commercial aircraft. Performancecharacteristics of the terminal can also be configured to meet or exceedthe operating threshold of GEO multicast service.

Dual Aperture Dual Modem SATCOM Terminal

With continued reference to FIG. 2 , the modem is further configuredwith a dual modem: 1) a broadband modem 220; and 2) a management modem210.

The broadband modem 220 is coupled, e.g., through a dedicated link, to abroadband aperture 230. The broadband modem 220 has a bidirectional link(transmit and receive) which can be configured to provide bidirectionalbroadband data service, e.g., Internet streaming and browsing, toairline passengers and crew via LEO satellites. The waveform of thebroadband modem 220 is configured to be compatible with the LEOsatellite system.

The management modem 210 is connected to the management aperture 200 ofthe antenna system with the receive-only link. A single receiver can beconfigured to function as the management modem 210 according to someembodiments, and have a waveform compatible with GEO multicast service.

As will be explained in further detail below, the management informationbroadcasted through the GSO satellite is used to assist the broadbandmodem 220 and broadband aperture 230 with acquiring communications linkswith NGSO satellites and performing handoff between NGSO satellites forbidirectional broadband data service through the broadband modem 220 andthe broadband aperture 230. The management information can be used tocontrol broadband antenna pointing and tracking of NGSO satellites,transceiver power management for transmissions to NGSO satellites,transceiver frequency correction for transmitting and receiving signalswith the NGSO satellites, transceiver timing synchronization fortransmitting and receiving signals with the NGSO satellites, etc., asdescribed below.

Broadband traffic, e.g., Internet traffic, can communicated to seatvideo display units and/or passenger electronic devices (PEDs) through aLAN distribution network and access points. Example PEDs include,without limitation, smart phones, table computers, laptop computers,gaming consoles, extended reality headsets, etc. The access points caninclude wired network connections, e.g., Ethernet, and can includewireless connections via, e.g., wireless local area network accesspoints. In some embodiments, IP television is streamed from a groundcontent server to a ground mission control center (300 FIG. 3 ) whichcommunicates the IP television through a GEO satellite gateway Earthstations for multicast distribution to GEO satellites. The managementmodem 210 via the management aperture 200 can receive the multicast IPtelevision traffic through the GEO satellite for distribution via theLAN distribution network to access to seat video display units and/orPEDs.

Although various embodiments are described in the context of themanagement aperture 200 and management modem 210 being configured andused to communicate with GSO satellites to receive management andcontrol information for use in controlling the broadband modem 220 andbroadband aperture 230 for communicating through NGSO satellites, insome other embodiments the management aperture 200 and the managementmodem 210 are configured to receive management and control informationfrom NGSO satellites. For example, the management and controlinformation could be received by the management aperture 200 andmanagement modem 210 through MEO satellites for use in controlling thebroadband modem 220 and aperture for communicating through LEOsatellites. The MEO satellites would necessitate less frequent satelliteswitching than LEO satellites and would provide benefit, although lessthan for GEO satellites, in obtaining updated management information foruse in controlling the broadband modem 220 and aperture forcommunicating through LEO satellites.

Moreover, although some embodiments are described in the context of thebroadband aperture 230 and broadband modem 220 being configured tocommunicate through LEO satellites, they may alternatively oradditionally be configured to communicate through another type of NGSOsatellites, such as MEO satellites. Thus, the management information maybe received through a GSO satellite for use in controlling acquisitionand performing handoff between MEO satellites that are used forbroadband communications.

Moreover, although some embodiments are described in the context of themanagement aperture 200 functioning as a unidirectional (receive only)antenna, in some other embodiments the management aperture 200 functionsas a bidirectional (transmit and receive) antenna.

It is to be understood that references made herein to GSO satellites canbe interchangeably referred to as GEO satellites and vice versa.

Operational Functions of Combined GSO and NGSO Satellite System

The operational functionality of the combined GSO and NGSO satellitesystem can be primarily divided into 1) Broadband and 2) Management &Multicast (M&M). FIG. 3 illustrates a block diagram with indicatedcommunications for the ground based and combined GSO and NGSO satellitesystem in accordance with some embodiments.

The system provides broadband data communications (e.g., high-speedInternet connectivity) through NGSO satellites, such as LEO satellites,using management and control information (also referred to as themanagement portion of M&M information) communicated through a GSOsatellite (e.g., GEO satellite). The system can be configured to providehigh bandwidth downlink and uplink channels delivering Gbps of speedwith a latency of below 50 milliseconds to a single aircraft. The systemis configured to switch to a new LEO satellite approximately every 5-6minutes. In a single flight, aircraft may operate through many differentLEO satellites spaced apart across several time zones. In doing so theaircraft antenna must closely track and switch between LEO satellites.Several landing stations (ground earth station) bridge LEO satelliteswith Point of Presence (PoP). The broadband communications are providedby a combination of broadband aperture and modem operations. However,they rely on the management path to receive critical management controlinformation such as satellite positions and associated time, altitudes,frequency plan, etc. as will be described in further detail below.

In FIG. 3 , the LEO mission control center 300 determines the managementand control information which is to be updated in the LEO satellitedatabase for transmission through a GEO satellite gateway Earth stationto a GEO satellite which relays the communications to aircraft basedSATCOM terminals operating in the GEO satellite coverage cell. Themanagement and control information is adapted to assist the aircraftbased SATCOM terminals with acquiring LEO satellites (or other NGSOsatellites) and performing handoff between LEO satellites during ongoingbidirectional broadband data service. As will be explained in furtherdetail below the LEO satellite database is updated to indicate positionsand associated times of the LEO satellites, signaling characteristics(e.g., frequency, timing, etc.) for the LEO satellites, and otherinformation for the LEO satellites.

To ensure uninterrupted broadband communication service (e.g., Internet)delivered via LEO satellites, the management and control information issent to the aircraft based SATCOM terminals via GEO satellites, whichform an “out-of-band” path relative to the LEO satellite paths. GEOsatellites provide an ideal pathway because they have the largestservice field-of-view and can effectively capture near-entire-globalcoverage with, e.g., only three ideally spaced satellites. Additionally,the relative position of the GSO satellite is fixed and predictablewhich facilitates communication link acquisition of the GSO satellite byan aircraft based SATCOM terminal. Commercial aircraft are highly mobileand can have an extended range of up to 19 hours. The LEO missioncontrol center 300 can provide a functional local interface between thebroadband and management paths which can be updated and synchronize themanagement and control information in, e.g., real-time. Additionally,multicast applications such as television service can be provided as afunction of the management path for reasons that are explained below.

In some embodiments, the LEO mission control center 300 transmits thesame set of positions and associated times and other information for allLEO satellites and associated ground stations through the set of GEOsatellites for use by the aircraft SATCOM terminals. In contrast, someother embodiments of the LEO mission control center 300 operate totransmit only a selected subset of the set of LEO satellites andassociated ground stations positions and other information transmittedthrough a selected one of the GEO satellites based on which of the LEOsatellites among the larger constellation of operational LEO satellitesare predicted to be within the service coverage area of the selected oneof the GEO satellites. Selectively transmitting the subset of LEOsatellite and associated ground station positions and other informationreduces the uplink and downlink resource utilization of the selected GEOsatellite path by avoiding transmission of position information for LEOsatellites that are not predicted to be presently within the servicecoverage area of the selected GEO satellite.

Challenges Addressed by Dual Aperture Dual Modem SATCOM Terminal

Various operational challenges and associated operational features whichcan be addressed by various dual aperture dual modem SATCOM Terminalsconfigured in accordance with embodiments of the present disclosure arenow explained.

Satellite Position and Time

The relative position of an LEO satellite changes in time. Antennadirection pointing and tracking of LEO satellites by the SATCOM terminalcan be effectively controlled using the management information receivedthrough the GEO satellite. A single aircraft during a flight route isserviced by many LEO satellites which may be in different inclination,altitudes, and ranges. Moreover, a single LEO satellite may service anaircraft for approximately 5-6 minutes or even less. When hundreds ofaircraft are considered in the large geographical region, it becomeschallenging to provide accurate LEO satellite position and associatedtime information updates to all aircraft. Without such information, thebroadband aperture antenna cannot be pointed toward a target LEOsatellite and cannot track movement of the target LEO satellite. Thisresults is complete loss of broadband service while the SATCOM terminalattempts to perform acquisition and handoff from one LEO satellite toanother LEO satellite.

These challenges are overcome by the system of FIG. 3 in which the LEOmission control center 300 acquires the position and associated timinginformation of all LEO satellites, and transmits the information throughthe GEO satellite gateway Earth station and GEO satellite for receipt bySATCOM terminals on aircraft within the service area of the GEOsatellite. The information is updated and periodically broadcasted toall such aircraft via GEO satellite. The management aperture 200 of theantenna on the aircraft SATCOM terminal receives the information andforwards part of the information to an Antenna Control Unit (ACU) 222(FIG. 7 ). The ACU 222 provides the pointing and tracking function forthe broadband antenna aperture.

Burst Time Plan Estimation

The broadband modem 220 employs time division multiple access (TDMA), sothe precise location of the LEO satellite in addition to the position ofaircraft (terminal) and ground Earth station (landing station) iscritical for transmitter and receiver signaling timing. The informationshared with the ACU 222 is therefore made available to the broadbandmodem 220 for use in performing precise TDMA burst time plan estimationand avoiding collision during LEO satellite acquisition, handoff andoperation. The broadband modem 220 acquires this information via themanagement modem 210.

Power Estimation and Control

Immediately after performing handoff between LEO satellites thebroadband modem 220 must transmit at a power level that is within thedynamic range of the demodulator and at correct level for error-freedemodulation of the acquisition or switched-to LEO satellite.Transmitting at high or low power may result in longer LEO satelliteswitch times or unsuccessful acquisition of the satellite beam.

The free space loss variation from highest to the lowest is negligiblein the GEO satellite. However, propagation variation from the best tothe worst has a factor of 4.68 in a LEO satellite with an altitude of610 Km, which will result in large free space loss variation. Whencontribution from both aircraft to LEO satellite and from satellite toground station, the combined variation can be as high as a factor of 12for a LEO satellite with an altitude of 610 Km.

In accordance with embodiments herein, information indicating the LEOsatellites positions and associated time and indicating the groundstation (GSO satellite gateway transmitter) position is broadcasted ormulticasted through the GEO satellite and received by the managementaperture and modem. The position of the ground station, satellite, andaircraft enables the broadband modem 220 to calculate the transmit poweraccounting for the free space loss at the time of transmission.Accordingly, providing the LEO satellite positions and associated timeand the ground station positions through the GEO satellite for receiptby the management modem 210, enables its use by the broadband modem 220to accurately predict and control the transit power while adjusting forthe free space loss.

Velocity Variations Between LEO Satellites and Aircraft

The relative velocity of the LEO satellite changes with respect to theaircraft based SATCOM terminal depending upon aircraft speed andheading. In reference to the aircraft based SATCOM terminal, a LEOsatellite rises at a relative low velocity then increases velocity untilpeaking, followed by falling velocity until the LEO satellite falls outof the range. FIG. 4 illustrates example velocity vectors of a pair ofLEO satellites relative to an aircraft velocity vector.

Frequency Drift and Doppler Correction for Velocity Changes Between LEOSatellites and Aircraft:

The SATCOM system comprising the GEO satellite gateway, GEO satellite,and aircraft terminal each experience frequency drift over time. Theactive Radio Frequency (RF) components such as oscillators, frequencysynthesizer, etc. contribute to frequency drift over time. Temperaturevariation is also the contributor in frequency shift in such equipment.Frequency change results in longer LEO satellite acquisition andhand-off time between LEO satellites by the aircraft based SATCOMterminal. Longer hand-off time may be acceptable if the recurrence ofhand-off is infrequent. However, in the LEO satellite system recurrencehand-off is relatively fast—approximately every 5-6 minutes. Threeprimary sources cause a frequency drift in the SATCOM system:

-   -   1) Ground station serving LEO satellite having frequency drift        over time;    -   2) LEO satellites having frequency drift over time; and    -   3) aircraft based SATCOM terminal having frequency drift over        time.

In addition to frequency drift, the Doppler frequency shifts are causedby:

-   -   1) Speed and direction of the LEO satellites; and    -   2) Speed and direction of the aircraft.

While a communication link is maintained between the aircraft basedSATCOM terminal and a LEO gateway via a LEO satellite, the communicationlink signaling can function to actively correct for frequency drift. Incontrast, when the aircraft based SATCOM terminal activates for thefirst time to attempt to acquire a LEO satellite or when it isperforming hand-off from one LEO satellite to the next LEO satellite,such uncertainty in frequency drift can cause a relatively long delay inthe LEO satellite acquisition and switch between LEO satellite, withresulting loss of broadband service during the delay period.

The management aperture 200 operating with the management modem 210 canreceive real-time information indicating the frequency drift from thesystem and velocity vector of the satellite. Position information of theaircraft accessible via ARINC 429 communication bus or GPS provides datato compute velocity vector of the aircraft. Such information is suppliedto the broadband modem system. With the raw information, the modemestimates the precise receive and transmit frequency for thetransceivers connected to the broadband aperture 230, accounting forfrequency drift from all components. The information enables rapid,e.g., instantaneous, LEO satellite switching with negligible switchoutage. Without availability of this information, approximately 6seconds of broadband service outage is expected to occur during eachhandover (handoff) procedure to switch between LEO satellites.

Multicast IP Television and Other Content

An individual LEO satellite serves an aircraft terminal for only for fewminutes due to the high velocity of the LEO satellite. As a result, ifmulticast IP television and other content were to be distributed throughLEO satellites, the IP television and other content would need to beconcurrently distributed to several LEO satellites interconnected bymany corresponding ground earth stations. Scaling the need formulticasting the IP television and other content to several hundredaircraft results in replication of multicast bandwidth by a largefactor.

In contrast according to some embodiments of the present disclosure, IPtelevision and other content is distributed from a GEO satellite gatewayEarth station through a GEO satellite to all aircraft within the servicearea of the GEO satellite. Distributing such IP television and othercontent to a large number of aircraft in a continental-size region thenonly necessitates one multicast path, which reduces the need to send themultiple replica of same multicast content distribution of IP televisionand other content.

FIG. 5 illustrates a block diagram of an aircraft based SATCOM terminalaccording to some embodiments of the present disclosure. Referring toFIG. 5 , the management aperture 200 and the management modem 210receive the multicast stream via a GEO satellite, with occasionalhandoff occurring between GEO satellites depending upon location androute traveled by the aircraft. All aircraft based SATCOM terminals,configured with dual aperture dual modem SATCOM configurations orsimilar terminals, are capable of receiving the same stream of multicastin a relatively large geographic area covered by the wide GEO satellitebeam. The multicast stream and therefore contain not just the management& control information used for acquiring and performing handoff betweenLEO satellites, but moreover can contain IP television and othercontent.

The multicast IP television is separated from the stream of multicast bythe management modem 210 and forwarded to the aircraft headend, e.g.,inflight entertainment content server. For passengers, near-real-timemulticast IP television is accessible from the aircraft headend via seatinflight entertainment (IFE) systems (e.g., seatback IFE displays andaudio interfaces) and/or via wireless IFE (W-IFE) distributed throughwireless access points for playout through PEDs. Passengers can therebywatch multicast television on seatback displays, armrest displays, cabinpartition displays, overhead displays, and/or via a myriad of passengertransported PEDs such as smart phones, tablet computers, and laptopcomputers.

The management and control information from the multicast stream isforwarded to an onboard processor. The onboard processer may residewithin the management modem 210 and/or the broadband modem 220. Theprimary information can include:

-   -   1) LEO satellite position and time in an industry-standard        format such as North American Aerospace Defense Command (NORAD)        Two Line Element Set (TLE);    -   2) Ground earth station information such as location, altitude,        and feeder link characteristics to satellites; and    -   3) Radio Frequency (RF) information of uplink and downlink path        such as center frequency, symbol rate, frequency oscillator        drift, antenna scan loss, polarization type, etc.

TLE is a data format encoding a list of orbital elements of the LEOsatellites for a given point in time, the epoch. A prediction formulaprocesses the TLE to estimate the state (position and velocity) of theLEO satellites at any point in the past or future.

The mission control center 300 can receive LEO satellite positiontracking information from Telemetry Tracking and Command (TT&C) stationsgeographically spaced apart along the path of the LEO satellites 110,e.g., such as the TT&C 1 Station and TT&C 2 Station illustrated in FIG.3 .

Management and control information received as part of the multicaststream from the GEO satellite can be raw and require an onboardprocessor to further process. The onboard processor's functionalcapability may reside within the modem system to ensure the delay inreceiving raw data, processing, and forwarding is minimized. Suchinformation is used for precise and real-time computation and processingto enable.

-   -   1) Pointing and Tracking of the broadband aperture antenna        relative to the LEO satellites;    -   2) Doppler and frequency correction of the broadband modem 220        signaling through the broadband aperture 230;    -   3) Timing synchronization of the broadband modem 220 signaling        through the broadband aperture 230; and    -   4) Power management of the broadband modem 220 transmission's        signaling through the broadband aperture 230.

Advantages of Multicast Television Distribution Through GEO Satellites

In accordance to some embodiments, multicast television is multicastthrough a GEO satellite in the same stream as the management and controlinformation. Multicast television is a primary method to deliver thetelevision content such as movies, television shows, news channels,financial information, sporting events, etc. Delivering televisioncontent over a network of LEO satellites and ground stations is complexand consumes significant frequency spectrum and processing resources. Aworksheet shown Table 1 provides comparative estimates of resourceconsumption for multicasting television content through LEO satellitesversus a GEO satellite in order to deliver the same television contentto aircraft based SATCOM terminals. FIG. 6 illustrates system componentsthat are used for multicasting content through a GEO satellite and formulticasting the same content through LEO satellites, in accordance withsome embodiments of the present disclosure.

TABLE 1 Multicast resource consumption worksheet GEO LEO ParametersSatellite Satellites Service Multicast Multicast Source Data Rate (Mbps)K K Terrestrial Multicast Replication 1 3 Terrestrial MulticastConsumption (Mbps) K 3 K Number of Beams Per Satellite 1 3 SatelliteMulticast Replication 1 3 Satellite Multicast Consumption Per SatelliteK 3 K (Mbps) Satellite Multicast Consumption Total (Mbps) K 9 K TotalMulticast Resource Consumption (Mbps) K 12 K 

Referring to Table 1 and FIG. 6 , for the GEO satellite multicastapproach, multicast content from a content source 600, e.g., IPtelevision server, is provided to the LEO mission control center 300(FIG. 3 ) for transmission through the gateway Earth station 304 to theGEO satellite 306 for relay to the aircraft based SATCOM terminals. Incontrast, for the LEO satellites multicast approach, the multicastcontent from the content source 600 is replicated and provided to threegateway Earth stations 310 for transmission through three correspondingLEO satellites 308 for relay to the aircraft based SATCOM terminals.

In both approaches, the K Mbps of multicast content is subject to bedelivered to all the aircraft based SATCOM terminals flying in a certainregion. In the LEO satellite multicast approach, the K Mbps isdistributed to three ground Earth stations terrestrially. This resultsin terrestrial total bandwidth consumption of 3×K Mbps. The same contentis uplinked to three LEO satellites with each consisting of three beams.Each LEO satellite will consume a bandwidth of 3×K Mbps for all threebeams. At the end, a total of 12×K Mbps of multicast bandwidth resourcehas been consumed to deliver the original content size of K Mbps. Insharp contrast, for the GEO satellite approach the same K Mbps is sentto the ground Earth station 304 terrestrially. The ground Earth station304 transmits the content in uplink to the GEO satellite 306 with alarge continental scale beam for distribution to all the aircraft basedSATCOM terminals within the service area of the GEO satellite 306. It isa factor of 12 additional resources required to deliver the same contentto all aircraft based SATCOM terminals in a given geographic area by LEOsatellites 310 versus the GEO satellite 306. Consequently, significantresource conservation can be achieved by multicasting television andother content through the GEO satellite 306 to the aircraft based SATCOMterminals.

When the aircraft based SATCOM terminals are configured with receiveonly management modems that operate to separate the multicast televisiontraffic for distribution to the aircraft headend, any associated returnpath communications for, e.g., packet retransmission requests, can beprovided through the broadband modem 220 and broadband aperture 230 viathe LEO satellites to the responsible Earth based network node, e.g.,the multicast content source 600.

Broadband Aperture Antenna Pointing and Tracking

Controlling pointing and tracking of the broadband aperture antenna area critical function of the aircraft SATCOM terminal. In a conventionalEarth based GEO satellite terminal, a fixed antenna is manually pointedto the target GEO satellite once during installation and can remainunchanged for its operational lifetime. In contrast, for mobileapplications such as aeronautical broadband services, aircraft motionnecessitates active control of where the aperture antenna is pointed totrack an acquired satellite. Because commercial aircraft travel at highspeed with extended range, providing broadband communications servicesusing a LEO satellite constellation provides many significantchallenges.

-   -   1) The aircraft SATCOM terminal requires position and time        information of all potential LEO satellites, and any time lag in        obtaining such information may result in miss-pointing relative        to a target LEO satellite.    -   2) An aircraft may be out of service for many days for        maintenance or other activities, during which time the SATCOM        terminal will not have access to satellite links to obtain        satellite position and time information due to lack of power        and/or being parked within the hanger blocking the links.    -   3) An aircraft antenna relies on a set of configuration        information to steer the antenna in a certain direction toward a        target satellite. When delivery of the configuration information        to the aircraft SATCOM terminal has not occurred, e.g., due to        failed satellite link, the terminal is unable to actively steer        the antenna toward any target LEO satellite.

The dual aperture dual modem SATCOM terminal disclosed herein overcomesthese challenges using a combination of LEO and GEO satellites, inaccordance with some embodiments.

-   -   1) A GEO satellite has a very large service coverage, ⅓rd of the        entire earth. A large field of view beam can cover an entire        continent such as the Americas.    -   2) A large GEO beam can deliver a multicast stream to an entire        continent. For example, all domestic aircraft can potentially be        covered in a single multicast stream.    -   3) The relative position of a GEO satellite is fixed. This gives        the most reliable path to deliver mission-critical information        for an aircraft broadband system. The aircraft which may be in        the hanger for maintenance and brought back to service after a        month still has a reliable link with GEO satellites to receive        management information that is used to control the broadband        modem 220 and aperture for acquiring and performing handoff        between NGSO satellites, such as LEO satellites.

The management aperture and the broadband aperture are independentlysteerable by operations performed by at least one processor. Themanagement aperture is steered by the operations toward a selected GSOsatellite and the broadband aperture is steered by the operations towarda selected one of the NGSO satellites. In accordance with someembodiments, the management aperture and/or the broadband aperture areat least one of: mechanically steered horn array; electronically scannedphased array; hybrid electro-mechanically steered array; and gimbaledreflector.

FIG. 7 illustrates a block diagram of an aircraft based SATCOM terminalconfigured according to some embodiments of the present disclosure.Referring to FIG. 7 , the management modem 210 and/or the onboardprocessor 510 can separate the multicast stream received through the GEOsatellite 100 into IP television and management & control information.The management & control information is processed by the onboardprocessor 510 to generate, for example: 1) pointing and trackinginformation for controlling pointing of the broadband aperture 230;Doppler frequency correction information controlling transmission andreception by the broadband modem 220; timing synchronization informationcontrolling timing of transmission and reception signaling by thebroadband modem 220; and power management information controllingtransmission signal power level of the broadband modem 220.

TLE data for all LEO satellites is part of the management and controlinformation extracted from the multicast stream. Three types ofinformation (among others) that are determined from the management andcontrol information include the latitude, longitude, and altitude of LEOsatellites as a function of time.

On the aircraft side, two primary possible sources provide the latitude,longitude, attitude, and altitude of the aircraft and an indication oftime. One such source is the ARINC 429 communication bus 700 which canprovide aircraft navigation information. Another source is a GPSreceiver and accelerometer 710 which can be part of the overall antennasystem. Either of these sources 700 and 710 provides the key locationinformation of the aircraft in a given time. The GPS receiver andaccelerometer 710 can be a better source of aircraft locationinformation because of its lower latency relative to obtaining suchinformation through the ARINC 429 communication bus 700.

The combination of the satellite position and aircraft position allowsan Antenna Control Unit (ACU) 222 (FIG. 7 ) to compute the pointinginformation—elevation angle and azimuth angle at a given time. Thepointing information is used to control the antenna aperture to bedirected to the target LEO satellite for transmitting and receiving datavia the target LEO satellite. If service is disrupted in mid-flight dueto miss-pointing or miss-tracking, the new LEO satellite position andtime information will be quickly obtained through updates inflight overthe GEO satellite 100 using the management aperture 200 and managementmodem 210.

Transmission Power Level Management by Aircraft SATCOM Terminal

FIG. 8 illustrates a block diagram of an aircraft based SATCOM terminalconfigured according to some embodiments of the present disclosure.Referring to FIG. 8 , transmission power level management is a criticalpart of satellite communication. Transmissions toward LEO satellitesinvolve multi-dimensional variables which need to be computed inreal-time and which complicates the estimation of an optimaltransmission power level. Once the aircraft SATCOM terminal is alreadylinked through a LEO satellite 110 to a LEO gateway Earth station 310(FIG. 3 ), the aircraft broadband modem 220 operates with the LEOgateway Earth station 310 (FIG. 3 ) to determine and control thebroadband modem 220 to transmit at an optimal power level toward the LEOsatellite 110. However, when the broadband modem 220 is attempting toinitially acquire the LEO satellite 110 or to switch to another LEOsatellite 110, the broadband modem 220 will require additionalinformation to ensure it transmits at an acceptable power level that canbe effectively received by the LEO satellite and associated gatewayEarth station 310 (FIG. 3 ). The challenges can include that excessivetransmission power level can saturate the LEO satellite front-endcircuitry, exceed a regulatory limit, and/or result in an unsuccessfullink by exceeding the dynamic window. In contrast, insufficienttransmission power level can fail to establish a communication link withthe LEO satellite.

Because the relative LEO satellite position rapidly changes inreal-time, the distance between the aircraft terminal and LEO satelliterapidly changes—also referred to by slant range between the receiver andtransmitter. The distance is furthest at the horizon, reduces tosmallest at the zenith, and then grows back to the furthest as the LEOsatellite falls out of the horizon. The free space path loss is directlyproportional to the slant range. A transmitter operating with inaccurateslant range may transmit at a power level too high or too low resultingin possible failed handoff to a new LEO satellite, failed acquisition toa new LEO satellite, and result in a long hand-off time to join a newLEO satellite.

The multicast management and control information processed by theonboard processor 510 can include TLE and RF data. The LEO satelliteposition information-latitude, longitude, and altitude are extracted asa function of time. On the other hand, the precise location of theaircraft is available via GPS and accelerometers 710 as a part of theantenna system or via ARINC 429 communication bus 700. Two sources ofinformation are processed to calculate the distance between the aircraftterminal and LEO satellite—called Slant Range A in FIG. 8 . Similarly,the ground Earth station location data is part of multicast managementand control information. The LEO satellite position data and groundEarth station position data are used for estimation of the distancebetween the LEO satellite and ground Earth station—called Slant Range Bin FIG. 8 . The broadband modem 220 uses the two slant ranges toestimate the transmission power level to be used for transmission at thetime of LEO satellite switching. One slat range information is needed ifthe LEO satellite is equipped with onboard modulation and demodulation.Other information such as frequency of the entry channel and antennagain at a given scan angle can be used in estimation of the transmissionpower level to be used for transmission as a function of time.

Doppler and Frequency Correction by Broadband Modem of Aircraft SATCOMTerminal

FIG. 9 illustrates a block diagram of an aircraft based SATCOM terminalconfigured according to some embodiments of the present disclosure.Referring to FIG. 9 , the velocity of a LEO satellite is relatively highcompared to the aircraft terminal. A LEO satellite orbiting at analtitude of 610 Km has a velocity of 7.55 Km/sec. The velocity of thecommercial aircraft could as high as 926 Km/hr. More importantly, therelative velocity changes when the heading directions of the aircraftand orbiting LEO satellite at a certain altitude are considered. Inaccordance with some embodiments, the SATCOM terminal is configured tocompensate for changes in the relative velocity and acceleration by,e.g., adjusting the broadband modem frequency to compensate for the rateof change and absolute change in Doppler frequency.

In addition, the three primary systems, ground Earth station, LEOsatellite, and aircraft SATCOM terminal each have an oscillator that issubject to drift in frequency. In accordance with various embodiments,the aircraft SATCOM terminal is configured to be informed of thefrequency drift of the ground Earth station and LEO satellites (e.g.,frequency drift values for the ground Earth station and LEO satellites)through the management information received via the GEO satellite 100and extracted by the management modem 210 and processed by the onboardprocessor 510. The onboard processor 510 can perform operations tocontrol the broadband modem 220 to compensate for the oscillator driftof the ground Earth station and LEO satellite indicated by the receivedmanagement information, and to further compensate for the oscillatordrift determined for the broadband modem 220 itself. Without suchoscillator drift compensation, the broadband modem 220 may need to scanthe possible frequency range used by the LEO satellite which would delayacquisition and/or handoff between LEO satellites 110.

Similar to previous processes, multicast management and controlinformation processed by the onboard processor 510 includes TLE, groundEarth station position, and RF data. The TLE data is processed tocalculate the real-time velocity of the LEO satellites 110. The aircraftlocation data from ARINC 429 bus 700 or GPS 710 is processed tocalculate the real-time velocity of the aircraft. The two velocityvectors are used to determine the relative velocity between a particularLEO satellite and aircraft SATCOM terminal. The management and controlinformation includes operating frequency and frequency drift of theparticular GEO satellite 110 and a LEO ground Earth station 310 pairedwith the particular GEO satellite 110. The operating frequency alongwith relative velocity are used to determine the Doppler frequencydrift. The frequency drifts, primarily caused by oscillators due tofactors like ambient temperature, is used with the determined Dopplerfrequency to determine with the final frequency estimation.

When seeking to acquire a communication link with a first LEO satellite,the broadband modem 220 uses the frequency estimation performed usingthe management and control information relating the first LEO satelliteto tune the transmitter and receiver frequencies to communicate with thefirst LEO satellite. In contrast, when seeking to perform handoff fromthe first LEO satellite to a second LEO satellite, the broadband modem220 uses the frequency estimation performed using the management andcontrol information relating the second LEO satellite to tune thetransmitter and receiver frequencies to communicate with the second LEOsatellite.

Timing Synchronization by Broadband Modem of Aircraft SATCOM Terminal

FIG. 10 illustrates a block diagram of an aircraft based SATCOM terminalconfigured according to some embodiments of the present disclosure.Referring to FIG. 10 , the LEO satellite system may employ Time DivisionMultiple Access (TDMA) and/or beam hopping. Both capabilities are highlydesirable but sensitive to varying propagation delays. The position ofthe LEO satellites relative to the aircraft continuously changes. Thedifference in change is largest when the aircraft SATCOM terminal needsto perform handoff from one LEO satellite to another LEO satellite. Asexplained above, the aircraft SATCOM terminal needs to frequently (e.g.,every 5-6 minutes) perform handoff to switch to a new LEO satellite withdifferent orbital properties. It is important for the broadband modem220 to have an accurate time estimation for transmission and receptionopportunities for communications with a LEO satellite. An inaccuratetime estimation can result in burst time collision with failed or slowacquisition of a LEO satellite and lack of timing synchronizationbetween hopped satellite beam and terminal.

In accordance with some embodiments, the management and controlinformation obtained through the GEO satellite 100 is used tosynchronize the transmission and receiving opportunity timing. Locationdata for the LEO ground Earth station, the LEO satellite, and theaircraft are used to determine a communication opportunity burst timeplan for the broadband modem 220 to transmit signals toward a LEOsatellite and to receive signals from the LEO satellite. The TLE dataprovides raw information about LEO satellite location with time.Similarly, the management and control information includes the locationof the ground Earth station. The aircraft position data is obtained fromeither ARINC 429 bus 700 or GPS 710. The position of the aircraft andLEO satellite can be obtained in real-time. Hence, the velocity vectorbetween the aircraft and LEO satellite can be also determined inreal-time. The position of the ground Earth station does not change,except when handoff is performed to a new LEO satellite which is pairedto a different ground Earth station.

The next step is to process the position data to calculate thepropagation delay in real-time. The broadband modem 220 uses thepropagation delay coupled with the command information to tunes thereceiver and transmitter according to computed burst time and burstwindow. The burst time is generally referenced to a nominal time anddelay. The burst windows could be nanoseconds to milliseconds. Theprecision of burst time must be very high. An error in the computeddistance between the LEO satellite and aircraft positions can result ininaccurate burst time delay failing to access the LEO satellite.

FIG. 11 illustrates a block diagram of a dual aperture dual modem SATCOMterminal which is configured according to some embodiments of thepresent disclosure. Referring to FIG. 11 , the management aperture 200receives management and control information from a GEO satellite whichis provided to the management modem 210 for extraction. The managementand control information is processed by the onboard processor 510 andused to control operation of the broadband modem 220 and pointing andtracking of broadband aperture 230 as explained in the embodimentsabove. As explained above, the onboard processor 510 can providebroadband data, such as streaming video, streaming audio, files, onlinegaming data, Internet browser data, cellular communications data, etc.which is received through the broadband aperture 230 and broadband modem220 to the inflight cabin network for receipt by inflight entertainmentsystems and/or PEDs. The inflight cabin network can include wired (e.g.,Ethernet) and/or wireless networks (e.g., WLAN). The onboard processor510 can also distribute broadcast television which is received throughthe management aperture 200 and management modem 210 to an IFE headendto allow passenger selection among the broadcasted television channels.

Further Definitions and Embodiments

In the above-description of various embodiments of present inventiveconcepts, it is to be understood that the terminology used herein is forthe purpose of describing particular embodiments only and is notintended to be limiting of present inventive concepts. Unless otherwisedefined, all terms (including technical and scientific terms) usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which present inventive concepts belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of this specification andthe relevant art and will not be interpreted in an idealized or overlyformal sense expressly so defined herein.

When an element is referred to as being “connected”, “coupled”,“responsive”, or variants thereof to another element, it can be directlyconnected, coupled, or responsive to the other element or interveningelements may be present. In contrast, when an element is referred to asbeing “directly connected”, “directly coupled”, “directly responsive”,or variants thereof to another element, there are no interveningelements present. Like numbers refer to like elements throughout.Furthermore, “coupled”, “connected”, “responsive”, or variants thereofas used herein may include wirelessly coupled, connected, or responsive.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. Well-known functions or constructions may not be described indetail for brevity and/or clarity. The term “and/or” includes any andall combinations of one or more of the associated listed items.

It will be understood that although the terms first, second, third, etc.may be used herein to describe various elements/operations, theseelements/operations should not be limited by these terms. These termsare only used to distinguish one element/operation from anotherelement/operation. Thus, a first element/operation in some embodimentscould be termed a second element/operation in other embodiments withoutdeparting from the teachings of present inventive concepts. The samereference numerals or the same reference designators denote the same orsimilar elements throughout the specification.

As used herein, the terms “comprise”, “comprising”, “comprises”,“include”, “including”, “includes”, “have”, “has”, “having”, or variantsthereof are open-ended, and include one or more stated features,integers, elements, steps, components or functions but does not precludethe presence or addition of one or more other features, integers,elements, steps, components, functions or groups thereof. Furthermore,as used herein, the common abbreviation “e.g.”, which derives from theLatin phrase “exempli gratia,” may be used to introduce or specify ageneral example or examples of a previously mentioned item, and is notintended to be limiting of such item. The common abbreviation “i.e.”,which derives from the Latin phrase “id est,” may be used to specify aparticular item from a more general recitation.

Example embodiments are described herein with reference to blockdiagrams and/or flowchart illustrations of computer-implemented methods,apparatus (systems and/or devices) and/or computer program products. Itis understood that a block of the block diagrams and/or flowchartillustrations, and combinations of blocks in the block diagrams and/orflowchart illustrations, can be implemented by computer programinstructions that are performed by one or more computer circuits. Thesecomputer program instructions may be provided to a processor circuit ofa general purpose computer circuit, special purpose computer circuit,and/or other programmable data processing circuit to produce a machine,such that the instructions, which execute via the processor of thecomputer and/or other programmable data processing apparatus, transformand control transistors, values stored in memory locations, and otherhardware components within such circuitry to implement thefunctions/acts specified in the block diagrams and/or flowchart block orblocks, and thereby create means (functionality) and/or structure forimplementing the functions/acts specified in the block diagrams and/orflowchart block(s).

These computer program instructions may also be stored in a tangiblecomputer-readable medium that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablemedium produce an article of manufacture including instructions whichimplement the functions/acts specified in the block diagrams and/orflowchart block or blocks. Accordingly, embodiments of present inventiveconcepts may be embodied in hardware and/or in software (includingfirmware, resident software, micro-code, etc.) that runs on a processorsuch as a digital signal processor, which may collectively be referredto as “circuitry,” “a module” or variants thereof.

It should also be noted that in some alternate implementations, thefunctions/acts noted in the blocks may occur out of the order noted inthe flowcharts. For example, two blocks shown in succession may in factbe executed substantially concurrently or the blocks may sometimes beexecuted in the reverse order, depending upon the functionality/actsinvolved. Moreover, the functionality of a given block of the flowchartsand/or block diagrams may be separated into multiple blocks and/or thefunctionality of two or more blocks of the flowcharts and/or blockdiagrams may be at least partially integrated. Finally, other blocks maybe added/inserted between the blocks that are illustrated, and/orblocks/operations may be omitted without departing from the scope ofinventive concepts. Moreover, although some of the diagrams includearrows on communication paths to show a primary direction ofcommunication, it is to be understood that communication may occur inthe opposite direction to the depicted arrows.

Many variations and modifications can be made to the embodiments withoutsubstantially departing from the principles of the present inventiveconcepts. All such variations and modifications are intended to beincluded herein within the scope of present inventive concepts.Accordingly, the above disclosed subject matter is to be consideredillustrative, and not restrictive, and the appended examples ofembodiments are intended to cover all such modifications, enhancements,and other embodiments, which fall within the spirit and scope of presentinventive concepts. Thus, to the maximum extent allowed by law, thescope of present inventive concepts are to be determined by the broadestpermissible interpretation of the present disclosure including thefollowing examples of embodiments and their equivalents, and shall notbe restricted or limited by the foregoing detailed description.

What is claimed is:
 1. A ground-based control center comprising: atleast one processor; and at least one memory storing instructionsexecutable by the at least one processor to perform operations to:generate non-geostationary orbit (NGSO) satellite management informationindicating positions and associated time of a set of NGSO satellites;communicate the NGSO satellite management information to mobilesatellite communication (SATCOM) terminals through communications thatdo not pass through any of the NGSO satellites in the set of NGSOsatellites, wherein the mobile SATCOM terminals are configured to usethe NGSO satellite management information to acquire the NGSO satellitesin the set for broadband communications.
 2. The ground-based controlcenter of claim 1, wherein the operations generate the NGSO satellitemanagement information to indicate positions of a set of medium earthorbit (MEO) satellites, a set of low earth orbit (LEO) satellites, or aset of highly elliptical orbit (HEO) satellites.
 3. The ground-basedcontrol center of claim 1, wherein the operations: identify a first setof NGSO satellites within a service coverage area of a firsttransmitter; generate first NGSO satellite management informationindicating positions and associated time of the first set of NGSOsatellites; communicate the first NGSO satellite management informationthrough the first transmitter to mobile SATCOM terminals within theservice coverage area of the first transmitter; identify a second set ofNGSO satellites within a service coverage area of a second transmitter;generate second NGSO satellite management information indicatingpositions and associated time of the second of NGSO satellites; andcommunicate the second NGSO satellite management information through thesecond transmitter to mobile SATCOM terminals within the servicecoverage area of the second transmitter.
 4. The ground-based controlcenter of claim 1, wherein the operations communicate the NGSO satellitemanagement information through at least one geostationary orbit (GSO)satellite gateway Earth station and at least one GSO satellite to themobile SATCOM terminals configured to use the NGSO satellite managementinformation to acquire the NGSO satellites in the set during handoffswitching between the NGSO satellites in the set for broadbandcommunications.
 5. The ground-based control center of claim 4, whereinthe operations: identify a first set of NGSO satellites within a servicecoverage area of a first GSO satellite; generate first NGSO satellitemanagement information indicating positions and associated time of thefirst set of NGSO satellites; communicate the first NGSO satellitemanagement information through the first GSO satellite to mobile SATCOMterminals within the service coverage area of the first GSO satellite;identify a second set of NGSO satellites within a service coverage areaof a second GSO satellite; generate second NGSO satellite managementinformation indicating positions and associated time of the second ofNGSO satellites; and communicate the second NGSO satellite managementinformation through the second GSO satellite to mobile SATCOM terminalswithin the service coverage area of the second GSO satellite.
 6. Theground-based control center of claim 4, wherein the operations:broadcast through the at least one geostationary orbit (GSO) satellitegateway Earth station and the at least one GSO satellite to an aircraftbased SATCOM terminals, at least one of: broadcast-multicast mediastreaming content including at least one of live television, Internetprotocol television traffic, and audio streaming, andbroadcast-multicast data transfer content including at least one ofairline operational data, weather maps, on-board content updates, andcaching information.
 7. The ground-based control center of claim 1,wherein the operations communicate the NGSO satellite managementinformation to aircraft based SATCOM terminals configured to use theNGSO satellite management information to acquire the NGSO satellites inthe set during handoff switching between the NGSO satellites in the setfor broadband communications.
 8. The ground-based control center ofclaim 7, wherein the operations communicate the NGSO satellitemanagement information through at least one geostationary orbit (GSO)satellite gateway Earth station and at least one GSO satellite to theaircraft based SATCOM terminals configured to use the NGSO satellitemanagement information to acquire the NGSO satellites in the set duringhandoff switching between the NGSO satellites in the set for broadbandcommunications.
 9. The ground-based control center of claim 1, whereinthe operations generate the NGSO satellite management information toindicate latitude, longitude, altitude, and associated time of the NGSOsatellites in the set.
 10. The ground-based control center of claim 9,wherein the operations further generate the NGSO satellite managementinformation to indicate latitude, longitude, and altitude of the atleast one geostationary orbit (GSO) satellite gateway Earth station. 11.The ground-based control center of claim 1, wherein the operations:determine frequency drift of the set of the NGSO satellites and/orfrequency drift of at least one NGSO ground station serving the NGSOsatellites in the set; and generate the NGSO satellite managementinformation to indicate the frequency drift.
 12. The ground-basedcontrol center of claim 1, wherein the operations: determine speed anddirection of the NGSO satellites in the set; and generate the NGSOsatellite management information to indicate the speed and direction ofthe NGSO satellites in the set.
 13. The ground-based control center ofclaim 1, wherein the operations: periodically generate updated NGSOsatellite management information for transmission to the mobile SATCOMterminals.
 14. A mobile satellite communication (SATCOM) terminalcomprising: a first modem configured to communicate throughnon-geostationary orbit (NGSO) satellites for broadband communications;a second modem configured to receive NGSO satellite managementinformation through another pathway than the NGSO satellites; at leastone processor; and at least one memory storing instructions executableby the at least one processor to perform operations to: receive the NGSOsatellite management information through the second modem, wherein theNGSO satellite management information indicates positions and associatedtime of a set of the NGSO satellites; acquire a second communicationlink with a second NGSO satellite among the set using the NGSO satellitemanagement information; and perform broadband communications through thefirst modem and the second communication link with the second NGSOsatellite.
 15. The mobile SATCOM terminal of claim 14, wherein the setof NGSO satellites is one of: a set of low Earth orbit (LEO) satellites;a set of medium earth orbit (MEO) satellites; and a set of highlyelliptical orbit (HEO) satellites.
 16. The mobile SATCOM terminal ofclaim 14, wherein the operations control directional pointing of abroadband aperture connected to the first modem based on a position andtime of one of the NGSO satellites determined from the NGSO satellitemanagement information to acquire the second communication link with thesecond NGSO satellite.
 17. The mobile SATCOM terminal of claim 16,wherein the operations: generate antenna pointing information based onlatitude, longitude, altitude, and associated time of the second NGSOsatellite determined from the NGSO satellite management information andbased on latitude, longitude, altitude, and associated time of theSATCOM terminal; and control the directional pointing of the broadbandaperture based on the antenna pointing information to acquire the secondcommunication link with the second NGSO satellite.
 18. The mobile SATCOMterminal of claim 14, wherein the operations control transmitter and/orreceiver signaling timing of the first modem for acquiring the secondcommunication link with the second NGSO satellite, based on location andassociated time of the second NGSO satellite indicated by the NGSOsatellite management information and based on location and associatedtime of the SATCOM terminal.
 19. The mobile SATCOM terminal of claim 14,wherein: the operations control transmission power level through anaperture toward the second NGSO satellite based on the position of thesecond NGSO satellite indicated by the NGSO satellite managementinformation, to acquire the communication link with the second NGSOsatellite.
 20. The mobile SATCOM terminal of claim 19, wherein theoperations to control transmission power level through the aperturecomprise to: estimate a first slant range between the second NGSOsatellite and a NGSO satellite gateway Earth station serving the secondNGSO satellite, based on latitude, longitude, and altitude of the secondNGSO satellite determined from the NGSO satellite management informationand based on latitude, longitude, and altitude of the NGSO satellitegateway Earth station determined from the NGSO satellite managementinformation; estimate a second slant range between the second NGSOsatellite and the SATCOM terminal, based on the latitude, the longitude,and the altitude of the second NGSO satellite determined from the NGSOsatellite management information and based on latitude, longitude, andaltitude of the SATCOM terminal; and estimate a transmission power levelto be used for transmission to acquire the communication link with thesecond NGSO satellite, based on the first and second slant ranges. 21.The mobile SATCOM terminal of claim 14, wherein: the NGSO satellitemanagement information further indicates frequency drift of the set ofthe NGSO satellites and/or frequency drift of at least one NGSOsatellite gateway Earth station serving the NGSO satellites; and theoperations estimate frequency to be used for receiving signaling fromthe second NGSO satellite during acquisition and/or to be used fortransmitting signaling to the second NGSO satellite during acquisition,based on the frequency drift indicated by the NGSO satellite managementinformation for the second NGSO satellite and/or for the NGSO satellitegateway Earth station serving the second NGSO satellite.
 22. The mobileSATCOM terminal of claim 14, wherein: the NGSO satellite managementinformation further indicates speed and direction of the NGSO satellitesin the set; and the operations estimate frequency to be used forreceiving signaling from the second NGSO satellite during acquisitionand/or to be used for transmitting signaling to the second NGSOsatellite during acquisition, based on the speed and direction of thesecond NGSO satellite indicated by the NGSO satellite managementinformation.
 23. The mobile SATCOM terminal of claim 14, wherein: thefirst modem comprises a broadband modem coupled to a broadband apertureand configured by the operations to establish the second communicationlink for bidirectional communications through the second NGSO satelliteusing the NGSO satellite management information; and the second modemcomprises a management and broadcast-multicast modem coupled to amanagement and broadcast-multicast aperture and configured by theoperations to receive the NGSO satellite management information from ageostationary orbit (GSO) satellite.
 24. The mobile SATCOM terminal ofclaim 23, wherein: the management and broadcast-multicast modem isconfigured by the operations for unidirectional receive-onlycommunications to receive the NGSO satellite management informationcontained in broadcast-multicast traffic from the GSO satellite, and thebroadband aperture is configured by the operations for the bidirectionalcommunications through the second communication link with the secondNGSO satellite.
 25. The mobile terminal of claim 23, wherein: themanagement and broadcast-multicast modem is configured by the operationsfor bidirectional communications to receive the NGSO satellitemanagement information contained in broadcast-multicast traffic from theGSO satellite and to transmit unicast traffic from users to the GSOsatellite.
 26. The mobile SATCOM terminal of claim 14, furthercomprising an electronically scanned phase array antenna having areceive-only physical aperture with multi-beam capability and atransmit-only physical aperture, wherein the receive-only physicalaperture of the electronically scanned phase array antenna is configuredby the operations to provide a first electronically steerable receivebeam steered toward the GSO satellite to receive broadcastcommunications including the NGSO satellite management information andis further operated to provide a second electronically steerable receivebeam steered toward the second NGSO satellite based on the NGSOsatellite management information to receive broadband communicationsfrom the second NGSO satellite, and wherein the transmit-only physicalaperture of the electronically scanned phase array antenna is operatedto provide an electronically steerable transmit beam steered toward thesecond NGSO satellite based on the NGSO satellite management informationto transmit broadband communications to the second NGSO satellite. 27.The mobile SATCOM terminal of claim 23, wherein: the management andbroadcast-multicast aperture and the broadband aperture areindependently steerable by the operations, the management andbroadcast-multicast aperture is steered by the operations toward aselected GSO satellite and the broadband aperture is steered by theoperations toward a selected one of the NGSO satellites.
 28. The mobileSATCOM terminal of claim 23, wherein: the management andbroadcast-multicast aperture and the broadband aperture are at least oneof: mechanically steered horn array; electronically scanned phasedarray; hybrid electro-mechanically steered array; and gimbaledreflector.
 29. The mobile SATCOM terminal of claim 23, wherein thebroadband communications comprise receiving at least one of streamingmovies, streaming music, streaming games, file transfers, and Internetbrowser data from ground based network content servers via the broadbandaperture and the second communication link with the second NGSOsatellite.
 30. The mobile SATCOM terminal of claim 23, wherein theoperations further receive from the GSO satellite through the managementand broadcast-multicast aperture: broadcast-multicast media streamingincluding at least one of live television, Internet protocol televisiontraffic, and audio streaming, and broadcast-multicast data transfersincluding at least one of operational data, weather maps, on-boardcontent updates, and caching information; and wherein the operations arefurther configured to receive the NGSO satellite management informationin periodic broadcasts from the GSO satellite.